The present invention relates in general to tracheal tubes for respirators and in particular to a new and useful device and method of evaluating the pressure in a balloon sleeve of the tracheal tube to determine if a ventilating operation utilizing the tracheal tube is valid.
While giving a patient artificial respiration by means of a closed tracheal tube such as the one disclosed in U.S. patent application Ser. No. 538,416 filed Oct. 3, 1983 (German application No. P 32 04 110.1-35), and a respirator which is designed for closed ventilation technique, the tracheal tube is applied in the trachea in a way such that its open end is directed to the carina and the lungs. By inflating a balloon sleeve embracing the tracheal tube, the tube is fixed to the wall of the trachea, and, along with the tube end at the side of the apparatus, seals the lungs against the larynx. With such a tube, the ventilation is effected through a thin flexible respiratory tube through which breathing gas is blown in and taken out by suction. A pressure measuring cannula, also extending into the tube, serves the purpose of measuring the intra-tracheal respiratory pressure and thus of controlling the respirator to produce in the lungs, the physiologically required breathing pattern.
If secretions from the tracheal and pulmonary region of the patient enter the open end of the pressure measuring cannula, clogging may be expected, and a risk arises of invalidating or stopping the pressure measuring operation. In such an event, the respiration control is unfavorably affected and the ventilation operation is not correct for the patient.